I currently cannot attach a focus particle to a wh-word because my wh-word is [ LIGHT + ] and the particle from the infostructure library says its MOD is [ LIGHT - ]. I see in Sanghoun’s thesis that [LIGHT + ] indicates a “word” while [ LIGHT - ] a phrase. I am not sure what that means. Is a bare NP like who a word or a phrase? For some reason which I am still investigating, my who NP is [ LIGHT + ] but Ivan NP is [ LIGHT - ].

Both Ivan and who are bare NPs in my two test sentences (who FOC arrived?Ivan FOC arrived). There is the difference that Ivan first goes through a lexical rule while who.NOM is fullform in the lexicon.

You don’t want the wh pronouns to go through bare-np because they already have their quantifiers (which_q_rel); giving them a non-empty SPR value would mean they have to go through bare-np, and then they’d get a second quantifier (exist_q_rel), which would mean broken MRSes.

You’re right that lex-synsem is likely the culprit. As for figuring out where it’s coming from, I suggest using the LKB to look at the expanded type for each of those supertypes. One or more will (probably) have [ SYNSEM lex-synsem ] and then you can trace backwards from those to see whose introducing it.

Looked at expanded type in the LKB starting from wh-pronoun-noun-lex and then each of the supertypes in turn, for as long as I was seeing lex-synsem in the type: wh-word-lex, norm-hook-lex-item, norm-ltop-lex-item.

norm-ltop-lex-item is still a lex-synsem while its supertype is lex-item and that one is a synsem.

How do I deal with it now? If I simply copy the same constraints, I imagine the effect will be still that my wh-pronoun will remain a lex-synsem. But then the constraints are meaningful (in the area which I still don’t fully understand).

After further conversation with @ebender, it looks like what should be changed here is not the wh-word but instead the particle. A particle of this sort attaches to words, not phrases, so it should require MOD < [ LIGHT + ] >.